1. Field of the Invention
This invention relates to contact printing and, more particularly, to novel and highly-effective magnetic contact printing apparatus which can make a large number of copy tapes from a single master tape at high speed.
2. Description of the Prior Art
There are many types of conventional magnetic printing apparatus that can make copy tapes from a master tape. Typically, a magnetic surface of the master tape having mirror-image patterns recorded thereon is brought into contact with the magnetic surface of a slave tape, and the magnetic patterns of the master tape are printed on the slave tape by applying a magnetic printing bias field.
In magnetic contact printing, the quality of the copied tape is substantially reduced by any slippage between the master tape and the slave tape, any air film that may form between the master tape and the slave tape, any misalignment of the respective edges of the master tape and the slave tape, and so on. Further, the life expectancy (projected service life, or the number of copies that can be made) is limited by mechanical damage to the master tape. Accordingly, the tape transport system for both the master tape and the slave tape must be constructed to ensure that the tapes run smoothly without any appreciable positional displacement in the width direction thereof and with suitable tape tension and little fluctuation of the tape tension.
Furthermore, in order to supply prerecorded tapes to the market economically, it is necessary to reduce the printing time. As a result, the contact printing apparatus is required to drive the tapes at high speed, and a computer is required to control the tape drive.
The life expectancy or projected service life of a new master tape is several thousands of printings. At a printing rate of several tens of tapes per hour, the same master tape may be used continuously over several days before it is worn out. From a production control standpoint, it is desirable to keep track of a variety of data such as the total number of prints to be made, the number of tapes already printed, the number of additional prints that may be made during the remainder of the useful life of the master tape, etc.